There is a trend in the art to provide electrical connectors having smaller dimensions, for e.g. providing multiple connectors in a restricted building space. However, with the electrical connectors becoming smaller and smaller, the electrically conductive inlays of those electrical connectors, i.e. the male pins and/or the female terminals, have to become smaller as well.
Wherein male pins can be manufactured with smaller dimensions (i.e. smaller cross section) very easily, it is more challenging to provide female electrical terminals having smaller dimensions. The difficulties arise, since for providing smaller terminals typically thinner metal sheets have to be used. However, providing terminals being manufactured from thinner metal sheets, results in reduced wall thicknesses of the terminal and thus to reduced contact forces that can be achieved between the male pin and the female terminal.
This is because contact forces of a terminal are typically generated by contact blades that are formed from a sheet of metal in which the contact blades are integrally formed with the terminal. Thus, the contact force that can be applied by a contact blade of a terminal on a pin is strongly dependent on the material used, i.e. the sheet material, and the sheet thickness. Consequently, with merely providing smaller terminals, the contact force applied on the male pin will become smaller. However, the smaller terminals have to fulfill the same contact force requirements, i.e. they have to apply the same contact forces on the male pin, as terminals that are manufactured from conventional thick sheet materials.
Particularly, high contact forces are required, to provide a secure electrical contact between the male pin and the female terminal even under rough environmental conditions, such as vibrations, shock and/or the like.
In the art, terminals are known that are provided with two contact blades being arranged in a stack, to provide increased contact forces between the terminal and a pin that can be mated with the terminal. Thus, both contact blades have to be lifted when the pin is mated with the terminal, thereby increasing the contact force. However, in these terminals, the contact force is directly dependent on the material thickness used. Thus, the required contact force limits the minimal sheet thickness so that terminals being provided with stacked contact blades cannot be provided at very small dimensions.
Further, contact blades are known having an L-shaped cross section. These contact blades achieve higher contact forces, since the moment of inertia of the cross section of the contact blade is increased, compared to conventional contact blades, having a substantially rectangular cross section.
An example for an L-shaped contact blade 10 is shown, in FIGS. 1A and 1B. When a pin 50 is inserted into the terminal 1, the contact blade 10 will be lifted, while rotating along its longitudinal axis. The longitudinal rotation leads to a decrease in contact area and is therefore disadvantageous. Further, due to the L-shaped cross section, the contact blade has larger dimensions, compared to conventional rectangular contact blades. Therefore, parts of the L-shaped contact blade are typically arranged to protrude out of the terminal body of the terminal. Thus, the terminal body is open to the environment and prone to contamination, with e.g. dust, oil, moisture and/or the like. Therefore, the contact condition between the pin and the terminal, i.e. the contact blade, can be negatively influenced. Further, with the contact blade protruding out of the terminal body, a potential risk arises, that the contact blade is unintentionally lifted off the contact pin during use, since the protruding parts might engage with other parts of the surrounding.
FIG. 1A shows an electrical terminal 1 in a cut view, without an electrical pin being inserted. The electrical terminal 1 includes a contact body portion 30 and an L-shaped contact blade 10. The L-shaped contact blade 10 has a contact portion 12 and a spring portion 14. FIG. 1B shows the electrical terminal 1 in a cut view in which an electrical pin 50 is inserted. As can be seen, upon inserting the electrical pin 50 into the electrical terminal 1, the contact blade 10 is twisted around its longitudinal axis, so that only a small area of the contact portion 12 remains in contact with the electrical pin 50. Thus, the electrical conductivity between the electrical pin and the contact blade is decreased. Further, the L-shaped blade is not formed symmetrical, so that it typically protrudes with the spring portion 14 out of the body of the terminal. Thus, there is a certain risk of an unintentional lifting off the contact blade 10, so that the electrical contact between the contact portion 12 and an electrical pin 50 is opened.
Therefore, there is a need in the art to provide female terminals that can be provided with small dimension, and that are configured to provide high contact. Further, the contact blade of a terminal should be protected from the environment.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.